Automatic and manual telephone-exchange system.



W. L. CAMPBELL Ge T. G. MARTIN.

AUTOMATIC AND MANUAL TELEPHONE EXCHANGE SYSTEM. APPucmoM FILED APILH.1901.

1 ,301 ,648, Patented Apr. 22, 1919.

3 SHEETS-SHEET I.

W. L. CAMPBELL 6: T. G. MARTIN.

AUTOMATIC AND MANUAL TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED APR-23.1907.

1,301,648. Patented Apr. 22,1919.

3 SHEETS-SHEET 2.

W. L. CAMPBELL & T G. MARTIN.

AUIOMATIC AND MANUAL TELEPHONE EXCHANGE SYSTEM.

APPucAnou mm APR. 23. 1901.

1,301 ,648. Patented Apr. 22,1919.

3 SHEETS-SHEET 3.

STATES PATENT OFFICE.

JVIIaSQN L. CAMPBELLJLND TALBOT G. MABTIN, OF CHIQA GO, ILLINOIS,ASSIGNORS, BY lIEfSNE' ASSIGNMENTS, TO AUTOMATIC ELECTRIC COMPANY, ACORPGBATION OF initiators.

.AIUTQMEAIICAND.MANUAL TELEPHONE-EXCHANGE SYSTEM.

Specifieation of Letters Patent Patented.Apr. 22,-1919.

Applicationfiled April 23, 1907. 'iseriahlTm 3695808.

' Toallwhom it may concern "F Bait known that we, WILSON L. CAMPBELLand*T-ALBorr G; MAn'ITN, both citizens of the United States of America,and residents of flvfihicago, .Gook county," Illinois, haveinventedacertain new and useful Improvement in sters or-calling devices.However, when a manual subscriber-calls van automaticsubw-iAutomatic'and Manual!Telephone-Exchange of the originating andtrunkin operators,

Systems, of which the =following is a speciulfiflfliblOIl. izOurinvention relates to telephone exchange skystems in generahbut moreparticuilarly tosystems in which both manual and 1 automatic apparatusis employed, and especially to; systems in which the subscriber ofamanual exchange may call and obtain con- ,nection with the line of asubscriber of an automatic exchange. One'of the: principal objects ofour invention is, therefore, the provision of an ar- I rangement wherebya manual subscriber may call .an automatic subscriber, through themedium of: orginating and trunking operators I cord: circuits, andvwhereby the origimating operator may have complete supervision over theconnectionthus established. As hereinafter described We accomplish this-.by ::providing an originating operators switchboard to which areconnected the lines 1 of manual subscribers. Suitable line-signali'sfliapparatus. is provided by which the subscribers may attract theattention of the operator, and on the same switchboard are one or morejacks connected with trunk lines extending to a trunking operatorsposition or 36'SWl'tcl1lb0aid. At the trunking operators position weprovide "one or more jacks connected with trunk lines leading to theautomatic exchange, and at the said exchange these trunk lines terminatein second-selec- 40 tors. In addition, the trunking operator is providedwith an impulse transmitter or cal ing' device by whic the saidselectors can be operated afte11 connection is made with one of thetrunk 'l iries leading thereto. We

-4 5 also equip the said automatic exchange with third-selectorsconnectors, the third-selectoi's being interposed between the second"selectors and the connectors, and all of these automatic"switches beingresponsive to the t0 impulse-transmitter or calling device includ ed inthe trunking opera-tors equipment. For the benefit of the automaticsubscribers,

and as a means of intercommunication bescriber, the manual-trunkingoperation, accomplished through they trunking operation corresponds tothe first digit o the called number, and the automatic trunking and:connectingoperations corresponding to the other four digits of thecalledcnumber are then accomplished at the automatic exchange, and areunder the control of the trunking operator. The trunking connection thusafforded between manual and automatic subscribers is supervised by theorigimating operator at the cord circuit of the latter at the manualexchange, and disconnect signals are'given when either or' bothsubseribers hang up their receivers. 'In this way-satisfactory serviceis given between the subscribers oflmanual and automatic exchanges, andats'theasame time, of course,

the manual subscribers can call manual subscribers, and the automaticsubscribers can call automatic subscribers.

It is'also an object, of course, to provide certain details and featuresof improvement and combinations tending to increase the generalefliciency' of a telephone exchange system.

To theforegoing and other useful ends, our invention consists inmattershereinafter set forth and claimed.

Inthe accompanyingrdrawings Figure 1 represents diagrammatically amanual substation Aconnected with a central ofiice in- .volvi-ngequipment usually found in a cen- -ilm'aticiexchangesg such asthe onethe switches of which are shown diagrammatically in Fig. 3 and whichwill be designated as the sub-automatic exchange.

Fi s. 1, 2 and 3 taken together show an estab ished connection extendingfrom the manual substation A (Fig. 1) to the automatic substation A(Fig. 3).

The substation A suitable or approved type. The one in connection withwhich we have elected to illustrate our invention comprises a receiver2, a switch-hook 3 for controlling the substation circuits, whichcontrolling operations are accomplished through the medium of anysuitable means, such as the cam-arms 4, 5 and 6. As the switch-hook islowered the cam-arm 4 momentarily presses the release springs 7, 8 and 9into engagement, whereby the substation line conductors may be groundedsimultaneously. When the switchhook is down the cam-arm 5 engages thespring 10, thereby bridging the ringer 11. across the line. Furthermore,when the switch-hook is down the said cam 5 disengages the springs 13and 14, thus breaking the local circuit which includes in series theprimary winding 15, transmitter 16 and local battery 17. The substationground circuit is normally broken between the ground springs 18 and 19by the cam-arm 6; but when said springs are together ground is providedto the ground post 20 and to the release spring 7, as is usually thecase in telephones of this type. The said substation comprises the usualinduction-coil 21 having the primary winding 15 and secondary windlng22. Bein an automatic substation it is provided wit the usual verticaland rotary impulse springs 23 and 24. Said substation is, of course,provided with a dial (not shown) which is secured to the shaft 25,together with the locking dog 26. Furthermore, there is a locking cam 27that locks the dog 26, while the receiver is on the switch-hook, toprevent a rotation of the dial. For operating the impulse sprin s 23 and24 the substation is provided wit an impulse wheel 28 that is secured tothe shaft, which im ulse wheel carries on its periphery the so-ca ledvertical impulse teeth 29 and one rotary impulse tooth 30. The saidimpulse teeth are so arranged that when the dial is drawn down thelmpulse springs 23 and 24 are not carried into contact with the groundpost 20; but as the dial returns, first the vertical teeth enga e thevertical impulse spring 23, and aer they have completed their work therotary impulse tooth 30 o crates the rotary impulse spring 24. In .t isoperation the subscribers vertical line conductor 31 is first given anumber of ground impulses, and then the rotary line conductor 32 isgiven one ground im ulse. It will be noticed that as long as the ial isout of normal position the construction is (Fig. 3) may be of any 7 suchthat the dog 26 permits the primary circuit springs 33 and 34 toseparate, thus preventin the impulses that are delivered to either lineconductor from ass to the other. The means whereby t esu scriber maysignal the called subscriber comprises the push-button sprin 35 whichnormally engages the contact point 36; but when the button 37 is pressedthe spring 35 engages the contact point 38, whereby the vertical lineconductor 31- may be grounded.

The second-selector D is substantially the same as the selector switchdisclosed in United States Letters Patent No. 815,321, granted March 13'1906, to Keith, Erickson and Erickson, with the exception that thereare no normal conductors. There is no necessity in the second-selectorfor a brid ecut-ofl' relay, and it is also omitted, and t e line relaysare. connected directly toithe battery lead. The private normalconductor of the said selector patent is of no utility in connectionwith the second-selector, and is also omitted. Since the said selectoris substantially like the one disclosed in said patent it is equippedwith a vertical magnet 39 and a rotary magnet 40, a release magnet 41and a private magnet 42, the operation of which will be understood. Thesaid private magnet 42, of course, controls the side switch wipers 43,44, 45 and 46, the said private magnet also controlling the circuit of'the vertical magnet 39, in the usual manner, by means of the springs 47and 48, but not of the release magnet, for the release magnet spring isomitted. The vertical movement of the switch shaft, and, therefore, ofthe wipers 49, 50 and 51, is controlled by the vertical magnet 39, andthe rotary motion by the rotary magnet'40, the rotary magnet circuitbeing provided with the usual interrupter springs 52, The operativemagnets of the switch are, of course, controlled by the subscriberthrough the medium of the vertical and rotary line relays 53 and 54, asis well known. Said re lays have under their control the usual springs55, 56 and 57, a'ndin addition the trunk release springs 58 and 59, bymeans of whichlatter springs the said switch may be released when theside switch wipers are in first or second position. By'means of theback-release relay 60 the release oi the switch D is brought about afterthe side switch has passed to third position. The third-selector E'(Fig. 3) is a duplicate of the second-selector switch D (Fig. 2).

The connector switch F is an im roved form of the connector described innited States Letters Patent No. 815,176, granted March 13, 1906, toKeith. Erickson and Eri kson. The general mechani al details of theconnector F are the same as those of the patented connector, but thereare changes in the. circuits. The connector switch shaft (not shown),like the switch shaft of the selector D, carries the line wipers 61 and62 and the private wiper 63.

i The connector switch is also controlled by the calling subscriberthrough the medium ofthe vertical and rotary line relays 63 and '64. Thevertical line relay 63 directly con trols the vertical magnet 65, andalso the 'rotary magnet '66 and ringer relay 67. The "ofl ice of thevertical magnet 65 is to give the shaft and shaft wipers their verticalmotion,

sand the rotary magnet 66 imparts to the shaft and shaft wipers a rotaryor circular motion. The-rotary line'relay 64. controls.

theprivate magnet 68,which latter, under certainconditions, controls inturn the vertical and rotary magnets 65 and 66, release magnet 69-, andalsothe side switch wipers 70, .71, 72, 73 and 74. 7 The side switch'of'the'connector, like the side switch of the first-selector, has a normalor first position, a second position and a third position. The releasemagnet 69 is also controlled by the line relays 63 and 64'conjointly. Bythe condensers 75 and 7 6 the circuit'through the connector isinductively divided into two sections. The connector F isalso providedwith the back-bridge coils 77rand 78, so arran ed that when the sideswitch passes to 'third position an energizin circuit is closed throughthe relay 78, which operates to connect the rotary line relay 64 to thecalled line. Thecentral ofiice is equipped with a busy-signalingapparatus of any suitable design, such, for example, as the onecomprising an interrupter 79 in series with the,..primary winding 804015the inductioncoill 81 whereby a. busy-signaling current is induced inthe secondary windingt82 of the coil. Th connector switch shaft alsocarries a normal post arm 83 which, when therconnector shaft is 03normal, allows the spring 84 to engage the contact point 85, whereby thebusy-signaling-current passes to the line of ;the calling subscriberwhen the side switch istin first position.

a The first-selector H .(Fig-.-3) allotted to the line of the-substationA is of the. type disclosed in saidselector atent.

It will be understood t at the manualexchange, which is shown in Fig. 1,and which may be designated as the main manual exchange, has allotted toit, of course, a plu rality of subscribers each provided with asubstation, such as the substation A.. These subscribers may readily beput in connection with one another through the medium of cord circuits,such as the cord circuit 0,1):- they may be put in connection with theautomatic subscribers of the main automatic exchange (Fig. 2), or of thesub-automatic exchange (Fig-3).

It will' further be understood ,that the main automaticexchange to whichthe se lectou D; 1 (Eig 2) belongs may lhaveallottedto it a plurality ofautomatic subscribers cash provided with a substation, such as thesubstation A (Fig. 3), each of which substations has allotted to it afirst-selector,

such as the first-selector H. The said firstselectors are adaptedi-to beoperated, in the manner well knownpto establish connection with asecond-selector, such as the secondselector D, and with other selectorsif necessary, which last selector is in turn adapted to establishconnection with local connectors, similar to the connector F, forobtaining connection with local subscribers. If it is desired to obtainconnection with the automatic subscribers of the sub-automatic exchange(Fig. 3) a second-selector, similar to the second-selector D, is, ofcourse, operated to a proper level from which trunk lines lead to thesub-automatic exchange (Fig. 3), among which is the'trunk line thatterminates in the selector E. The sub-automatic exchange alsohas'allotted to ita plurality of substations, such as the substation A,each of which substations has allotted to it a first-selector, exactlyas the substation A has allotted to it a first-selector.

The method of o eration of the system will be understood rom thefollowing: -If

the subscriber at the substation A (Fig. 1)

order circuit, transmit the order to one of the outgoingtrunkingoperators. The trunkingl operator upon receiving the order willdesignate to the subscriber-ls operator which trunk .to take. Thesubscribers operator "thereupon willplug in the jack of the designatedtrunk atthe same time that the trunking operator-selects one of thetrunk lines leadingtouthewmain automatic exchange It willbe..understoodthatif an. automatic subscriber were calling thenumbe'rl2922O he would; have to operate his dial five times, once inaccordance with each digit; but

:when a call comes from the manual subscriber A the preliminaryoperations of the line and trunking operators, above ex plained, willcorrespond to the operations of the automatic subscriber for the firstdigit 2, and consequentlywhen the trunking operator begins to operateher automatic calling device forcalling the said line #29220 the firstdigit is omitted. The trunkingoperator then operates her automaticcalling device inaccordance with the digit 9 to operatethe selectorDasha next operates her calling device in accordance with the seconddigit 2, for operating the selector E to connect with the connector F.Subsequently, the calling device is operated in accordance with the lasttwo di 'ts to operate the connector and for there y completing theconnection, if the line is idle.

In detail, the establishn'lent of the connection is as follows: When thesubscriber at substation A removes the receiver from the switch-hook anenergizing circuit is closed through the line relay 86. This circuitextends from ground Gr through the transmitter 87 of the substation A tothe armature 88 and to the contact point 89, to the line relay 86 andthence to the battery lead 90, and through battery B to ground G. Theline relay upon energizing operates to close in contact the armature 91and contact point 92, whereby the circuit is closed'through the linelamp 93. The operator upon observing this signal will answer in theusual manner by placing one of the answeri plugs p in the answering jackcorrespoiiging to the lamp. She then throws her key It to listen. Whenthe plug 2 engages the jack an energizing circuit is established throughthe line-cut-ofi relay 94. This circuit extends from ground ,G throughthe relay 94, through the sleeve of the jack to the sleeve of the plugp, relay 95, battery lead 90, thence through battery B to ground G. Therelay 94 upon energizing attracts its armatures 87 and 88 to engage withthe contact points 96 and 97, whereby the subscribers line conductorsare extended to the operators cordcircuit. Also, when the line-cutoflrelay thus operates, the substation A is supplied with battery currentfor talking purposes. This circuit extends from. the grounded terminalof the batter B throu h the relay 98 to the tip of the p ug p, to t etip of the jack 7, through the contact point 96 and armature 87, throughthe substation transmitter to the sleeve side of the line, through thearmature 88, contact point 97, sleeve of the jack and plug 7), throughthe relay 95 to the battery lead 90, and through battery B to ound G.The relays 95 and 98, being inc uded in this circuit, energize andattract their respective armatures 99 and 100. The operator upon learninthat the substation #29220 is wanted will, by pressing the order wirebutton q, transmit the order overthe line 0 to the outgoing trunkingoperator at J. The trunking operator at J upon receiving the signal willpress the button 9 and thus bridge the talking set is across the orderwire. Said. operator J u on receiving the order from the operator C willinstructthe operator C which trunk to use. The subscribers operator uponbe ing assigned a trunk will insert the plug p into the jack of thetrunk designated. At

the same time, furthermore, the trunking;

operator will select one of the trunk lines leading to the automaticexchange and insert the plug p ,of the trunk assigned to thesubscri'bers operator, into the Jack j When the plug 19' engages thejack j an energizing circuit is established through the relay 10]. atthe cord circuit C. This circuit extends from ground G at the trunking0perators position J through the relay 102, trunk conductor 103, throughthe sleeve of jack j and sleeve of plug 7), through the relay 101 to thebattery lead 90, and through battery B to ground G. The relay 102 uponenergizing withdraws its armature 104 from engagement with the groundedcontact point 178, and the relay 101 upon energizing attracts itsarmatures 105 and 106 to engage the contact points 107 and 108,respectively. When the armature 105 and contact point 107 engage, the tiside of the cord circuit is then completed through the condenser 109from the answering plug 19 to the calling plug p. When the armature 106and contact point 108 engage, a circuit is closed through the suervisory lamp 110. This circuit extends rom the grounded terminal G ofthe battery through the armature 111, contact point 112, through thelamp 110, armature 106 and contact point 108 to the battery lead 90 andthrough battery B to ground G. It will be made to appear hereinafterthat when the called, subscriber answers, this circuit through the lamp110becomes broken upon the energization of the relay 113. I Thus far theconnections have been made manually-that is, through 0 erators. Theautomatic continuation of t e manual connection commences at thetrunking operators calling device .d. Whenthe plug 10* is inserted inthe jack j an energizing circuit is established throu: h the releasingrelays 114 and 115. This circuit extends from the grounded ring of theplug 79 through the ring of the jack 3', relay 114 in series with therelay 115, to the battery lead 90, and through battery B to ground G.The relays 114 and 115 are provided for bringing about the automaticrelease of the automatic switches when the plug 79 is removed from thejack 7'. The relay 114 is a quick acting relay, while the relay 115 isarranged to operate slowl When the relays thus energize in series nitarmatures 116 and 117 of the relay 114 disengage from the contact points118 and 119 before the armature 120 of the relay 115 engages the contactpoint 121; and then when the relays denerg'ize, the armatures 116 and117 of the relay 114 engage their respective contact points before thearmature 12G disengages from the contact oint 121. Havin establishedconnection with the selector the first digit 2 of the number 29220 iseliminated, as already explained. The operator then throws the key 1: sothat the springs I30 175 and-177", respectively from the contact points1 76' and 178 andcarried into engagement with the contact points 179 and1 80", from which last-named contactpointsconductors lead to the callingdevice 05, which calling device is then operated in accordance with theremaining digits 9; 2, 2 and 0. Therefore, the so-called verticalpush-button 124 is pressed onto the ground spring 125 nine timeswhereby'the verticalline relay 53 of the second-selector D is energizednine times over a circuitex- I tend-ing from the grounded sprin 125through the spring 124, through the fiey 'k" to the =tip=oithe plug-pand the tip-side of the jal'ck 7"; conductor122, side switch wiper 43,vertical line relay 53 to the battery lead 130; and" through battery; Bto ground G: Each time that the vertioal'line relay 5351s energized the5 rings 55 and 56am pressed into contactyw ierehy an energizing circuitis closed. each time through the vertical magnet 39?" The verticalmagnet then operates to carry the shaft and shaftwipersi), 50 and 51nine steps and opposite the banklevel' in which terminate the trunklines leading to the sub-exchange in which the wline #29220 terminates.-After the callin de vice has been operated for the vertioa i-mpulse therotary push-button spring =13i"is pressed onto the ground spring 125once,

whereby a momentary energizing circuit is established through the rotaryline relay 54 of the selector D. This circuit extends from groundspring125 through the push-button spring 131'; key to the sleeve side ofithe I plug gu -and jack j conductor 123; side sw-i'tch 'wi per 441110the) rotary line relay fi if to the battery lead 130; and throughBattery B tc ground G; The rotaryline relayien ergi'zes and places thesprings 56 and Win contact, whereby an energizing circuit is closedthrough the private'magnet The private magnet upon energizing and 'den-'ergizi ng operates in the usual manner to permit the side switch to passfIOm'fiIfSttO When the side switch" second position. wiper45 tngages thegrounded contact point in'the' second position an energizing circuit isolesed' through the rotary magnet '46. 7 The rotary magnet now operatesto carry theshaftwipers 49, 50 and 51 in a rotarydirw tion and intoengagement with thenfirst set of 'trunk line contacts.-- If the firsttrunk lineis'busy an energizing circuit is =es tab-'- lished through theprivate magnet extendl ing from the grounded shaft wiperi 51 whichengages the busy contact, through the release relay 60, side switchwiper 46, which is in' seco nd position, to the private magnet 42,thence to the battery lead 130," and through battery B to ground G". Aslong as the private wiper 51 engages busy or grminded contacts theenergizing circuit through the private magnet 42 is main-- aredisconnected tained,- and theside switch is retained in second position,thus maintaining the energizing circuit through the rotary magnet 40.\Vhen the shaft wiper 51 passes'onto the first idle contact theenergizing circuit 70 through the private magnet becomes broken and theside switch passes from second to third positionythus extending thetrunk con (111915013 122 and 123 through the side switch 7 wipers 4-3and 44 to the trunk conductors 132 and 133 which lead-to 'thethird-selector Ed Fig. 3) located in thesub-exchange: It will be seen by-referring to Fig. 2 that in series with-the trunk line conductors132-and- 133-there are the-relays 134 and 135.- These relaysareprovidedin ordertha t the release:

i of the selec'torD may be brought about after the side switch haspassed to thirdposition. The-said-relays are'so arranged thatwhen eitherrelay energizes the springs 136'and" 137'do not engage; but when therelays ener gize simultaneouslythe springs 136 and-137 arepressed intocontact, thus closing a circuit through the release relay 60 of thesecon-dselec'tor D. The third digit being 2 the trunkingmperator pressesthe vertical pushhutton spring 124 onto the ground spring 125'twice,andthe rotary push button 131 is pressed onto'the ground spring 125once; This operation of the calling device closesanenergizingcircuittwice through the vertical linerelay 138 of the third selector E; and anenergizing circuit through the rotary relay 139'is'closed once. Thiscircuit through the verti'oal line relay: extends from the ground-i wcalrdireotroh and opposite: thelsecondlevellf ofi halnl'r contacts whichlead to the connector switches." After the vertical magnet-has thusoperated, the momentary circuit that is closed throughthe rotarylinerelay 139 may 1 be traiced from the ground spring-12fr at the 1 callingdevice 0! (Fig. 2) to the rotary trunk 1 conductor 123, thence throughthe side 1 switch wiper 44 of the selector D and U through the-windingof relay 135 to the ro tary trunk conductor-138, thence to thesideswitch wiper-153 of the selector- B, and

through the rotary line relay. 139 3130 thebattery lead 141, and throughbattery 13 to' ground G When the rotary line'relay139 is energized thespring 148is pressed into contact'tor a moment with the spring 142,

whereby a momentary energizingcircuit is closed through the privatemagnet 149, which latter now operates to shift the side switch fromfirst to second position, whereby an energizing circuit is closedthrough the rotary magnet 150. When the side switch wiper 151 engagesthe grounded contact point 152 the rotary magnet 150 is operated tocarry the shaft and shaft wipers 145, 146 and 147 into engagement withthe first idle trunk line conductor-leading connector. Assuming thatconnectlon is made with the connector F, then when the side switchwipers 140 and 153 pass to third position the trunk conductors 122 and123 are extended to the conductors 154 and 155 leading to the connectorF. The operations of the calling device for the last two digits (two andnaught) are directed to the connector switch F. Grounding the verticalline conductor 122 for the digit 2 now energizes the vertical line relay63 of the con-' nector F. The vertical line relay 63, being to aenergized twice, operates to close the springs Y 156 and 157inoontacuwhereby an energizing circuit is established twice through thevertical magnet 65. The vertical magnet 65 now operates to carry theshaft wipers 61, 62 and 63 in a vertical direction and opposite the banklevel in which are located the terminals of the normal conductors 158and 159 which lead to the substation conductors 31 and 32. When therotary line relay 64 is operated the privatemagnet 68 is energized andthe side switch passes from firstto second position. -When the sideswitch wiper 72 passes from first to'second posi tion the verticalmagnet 65 passes from the control of the vertical line relay, and the'rotary magnet 66 is substituted instead. Now, when the vertical linerelay v63 is up erated ten times for the last digit naught, the rotarymagnet 66 becomes energized ten times and the shaft wipersv 61, 62 and63" are rotated ten steps and onto the contacts which constitute theterminals of the normal conductors 158 and 159. Now when there-' taryline relay 64 is energized for the last time the private.magnet 68 is inturn energized, whichunow bperate's with one of two results, namely therele-aseof the side switch from second to third position,'or the.so-

called busy-release of the connector switch. It will be assumed that thefirst result takes place that is, that the sideswitch passes from secondto third position. If the called line is busy, then when the privatemagnet 68 energizes for the last rotary impulse the groundon the privatecontact of the called line is transmitted to the releasemagnet 69. Anenergizing circuit is then established extending from the groundedcontact point to the shaft wiper 63, side switch wiper 74 to the secondposition contact point, through the two upper springs of the privatemagnet 68 to the release magnet 69 and battery lead 141, thence throughbattery B to ground G. The release magnet upon ener 'zing operates torelease the switch sha and wipers, and to restore the side switch tofirst position. N ow when the substation signaling button is pressed thevertical magnet is energized and the switch shaft is raised, and thenormal arm 83 permits the springs 84 and 85 to engage, whereby thebusy-signaling coil 81 is connected to the line and the busy-signalingcurrent is transmitted to the calling subscriber. When the side switchwiper 74 engages the grounded contact point 160 a guarding potential isestablished at the private Wiper 63* to protect the called line. Thisguarding potential also closes an energizing circuit through thebridge-cut-ofi relay '161 of the first-selector This circuit extendsfrom the contact point 160 through the side switch wiper 74,

shaft wiper 63, conductor 162, through the spring 163, oontactpoint 164,bridge-cut-ofi relay 1 61 to the battery lead 141, and

through battery 13 to ground G It will be lay controls t esprings 166and167. Saidrelay energizes as soon as connection is closed with thecalled substation. The energizin'g circuit through the relay 78 extendsfrom the grounded contact point 160, throughthe side switch wiper 74,backbridge relay 77, throughthe ringer relay springs and side switchwiper 70, shaft wiper 61, through the hoIm-al. c'onductor158, lineconduotort31, through the switch-hook 3 to the ringer spring 10, throughthe ringer 11 to the rotary line conductor 32, rotary .normal conductor159, shaft wiper 62, side switch wiper 71, ringerjrelay springs to therelay 78, thence to the battery lead 141 and through battery B to groundG The relay 78 energizes and closes in contact the springs 166 and 167,as explained. The supervisory relay 168 at the trunking operatorsposition now energizes over a circuit extending through ound Gr to therelay 168, and through t e sleeve side of the cord circuit to the keyIt, to the rotary trunk conductor 123, side switch wiper 44, shaft wiper50, through the relay 135 to the rotary trunk conductor 133, side switchwiper 153, c0nductor 155, through the supervisory relay springs 166 and167 to the side switch wiper 73, rotary line relay 64 to the batterylead 141, and through battery 13 to ground G. It will be seen that therotary linerelav 64 is in this circuit, but the resistance of the coil168 is so high that said relay 64 does visory lamp 171.

not operatively energize. The relay 168 upon energizing closes incontact the armature 169 and the contact point 170, whereby a circuit isclosed through the back super- The back supervisory lamp 171 lights, butnot the front supervisory lamp 172, as the relay 102 is 'ener: gizedover the sleeve conductor from the calling plug of the originatingsubscriberss operator, as explained. At the same time, at the.subscribers operators position the back supervisory lamp, .110 isglowing, because battery current is cut oil from the tip trunk lineconductor by the supervisory relay 168 at the trunkin operatorsposition, and the relay 113 at t e subscribers operators position cannotenergize to attract its armature 111 from the contact point 112 untilthe supervisory relay 168 denergizes. The trunking operator after havingoperated the central oilice switches to establish connection with theline conductors leading to substation #29220 presses the verticalimpulse spring 121 onto the ground post 125, whereby an energizingcircuit is again completed through the connector vertical line relay 63.The vertical line relay upon operating closes an energizing circuitthrough the ringer rela 67. This circuit extends from round through'thesprings 157 and 156, t rough the private magnet springs 163' and 164',side switch. wiper 72, through the winding of the ringer relay 67 to thebattery lead 141, thence through battery B to ground G. The ringer relayupon energizing operates to bridge across the line conductors of thecalled substation the terminals of the ringer generator, whereby thesubstation ringer 11 isoperated. The subscriber at substation A ,1having been signaled by the trunking operator, removes the receiver 2from the switch-hook- 3, and upon referring to Fig. 3 itfwill beseenthat-a condenser 173 is in the receivercircuit, so that the circuitthrough the supervisory relay 78 in the connector F is broken, As aresult the springs 166 and 167 separate and the rotary trunk conductor1564s disconnected from the non-grounded pole of the battery. B this thesupervisory relay l68 is deenergize and the armature 169 fallsbackagainst the contact point 174, the back'supervisory lamp 171 isextinguished andthe tip trunk line conductor 103 is conneoted tothenon-grounded pole of the battery. .An energizing current now flowsthrough the relay 113 of the originating operators cord circuit. Thiscircuit extends from the grounded terminal G of the battery B throughthe relay 113, contact oint 107, armature 105, through the ti o the plug79 and tip spring of the jac: j, tip conductor 103, through the relay175, contact point 174, armature 169 to the battery lead 90,- andthrough battery B to ground G. The relay 113 energizes and attracts itsarmature 111 from contact with the point 112, whereby the circuitthrough the back supervisory lamp 110 becomes broken. The

supervisory lamps in both the subscribers and trunking operatorspositions now being extinguished, the operators will understand that thesubscribers are both onthe line. After having finished the conversationthe subscribers hang up their receivers. On the automatic side the backsupervisory relay 78 of the connector is again energized, since thecircuit is again closed through'the' relay-78 and the substation ringer,placing the-springs 166 and 167 in contact, whereby the circuit throughthesupervisory relay 168 at the trunking operators position is againcompleted. When this relay energizes, the armature 169disengages fromthe contact point 174, whereby the circuit through the relay 113 of thesubscribers operators cord' circuit becomes broken. The denergization ofthis relay 113 permits the armature'lll to engage the contact point 112,whereby the circuit through the back supervisory lamp 110 is againestablished. If now the manual subscriber at substation A hangs'up hisrecciver'also, the energizing circuit including the supervisory relay98'becomes broken and the armature 100 engages the contact point 176,whereby a circuit is completed through the front supervisory lamp 177.The operator seeing both the frontand back supervisory lamps lightedtakes down the connect1on. movedfrom the jack j the circuit includingthe relay 1020f thetrunking operators position, in series with'the relay101 of the sub scriberls cord circuit, becomes broken and the relay- 102Ideeuergizes, permittin the armature 104 to engagethe grounde con tactpoint 178. The engagement of the armature 104 and grounded contact point178 closes the circuit through the manual supervisory lamp 172 in thetrunking operators circuit. The trunking operator seeing both' lampslighted takes down the connection by pulling out the plug p from thejack j and as a result the energizing circuit through the release rela s114: and 115 is broken. The relay 114 eing a quickacting relay, asexplained, permits the armatures 116 and 117 to engage the contactpoints 118 and 119 before t e arma-- ture 120 of the slow-acting relay115 disengages from the contact point 121. By this action the trunk lineconductors 122 and 123 are grounded simultaneously for energizing thevertical and rotary line relays of the connector F. When said verticalandrotary line relays 63 and 64 of the connector F energizesimultaneously the trunlbrelease springs 179 and 180 are pressed intocontact, whereby a series energizing circuit is completed through therelease relay 181 of the. selector E and the release magnet 69 of theounded connector F. This circuit extends from the grounded contact point182 through the side switch wiper 183, release relay 181, through theprivate shaft wiper 147, springs 17 9 and 180, release ma et 69 to thebattery lead 141, and throug battery B to ground G. The release ma et69, upon energizing, operates in a wel -known manner to restore theconnector shaft wipers and side switch to normal position. The releaserelay 181 of the selector E, upon energizing, closes the springs 184 and185 in contact, whereby a circuit is closed through the release magnet186. The selector release magnet 186, upon energizing, attracts itsarmature and remains in readiness to restore the shaft wipers and sideswitch to normal position, when the ener 'zing circuit through therelease relay 181 ecomes broken, which occurs when the slow-actin relay115 deenergizes. Also, when the trun line conductors 122 and 123 aregrounded simultaneously, the relays 134 and 135 at the selector Denergize simultaneously, placin the springs 136 and 137 in contact,Where established through the release rela 60 of the selector D. Thiscircuit exten s from ground through the side switch wiper 46, releaserelay 60, shaft wiper 51, springs 136 and 137, resistance coil 187 tothe battery lead 130, and through battery B to ground G. The releaserelay 60 operates in turn to close in contact the springs 188 and 189,whereby a circuit is closed through the release magnet 41. The releasemagnet 41 energizes and attracts its armature, remaining in readiness torestore the selector shaft wipers and side switch to normal position,when the ener izing circuit through the said magnet is bro enth at is,when the slowacting relay 115 denergizes.

It will be seen that the supervlsion of theseconnections rests entirelywith the subscribers operator, because the trunking operator does nottake down the connection until signaled by the originating operator.Supervision of the signallng of the called subscriber depends on thetrunking operator, but the subscribers operator 1s also afforded meansto know when the called subscriber has answered. The button a (Flg. 2)is provided in order that the ground may be cut off from the armature120. This provision is made in order that the operator may remove theplug p and insert another without releasing the automatic selectorswitches. It will be remembered that when the plug is removed from thejack j the energizing circuit through the release relays 114 and 115 isbroken, and the armatures116 and 117 are placed in contact with thepoints 118 and 119 before the armature 120 disengages from the contactpoint 121, thereby grounding both trunk conductors 122 and 123; but ifthe button a is pressed the ground connecy an energizing circuit is tionis cut off from the armature 120, and the de'energizing of the releaserelays 114 and 115 is without effect, and the transfer of plugs andcords may be accomplished with out taking down the connection.

Suppose that the subscriber at substa tion A- desires connection with asubscriber of the manual exchange. In that event the calling end 1) ofthe cord circuit C is inserted in the jack corresponding to the desiredsubstation. The ringing key is operated, whereby ringing current fromthe ringer generator R is projected out on the called line.

It will be understood, of course, that in the automatic oflices of thissystem the firstselectors, as well as the second-selectors,third-selectors and connectors, are arranged in groups, saidsecondselectors, third-selectors and connectors being arranged on apercentage basis. For example, in an automatic exchange of ten thousandcapacity a somewhat common arrangement is to divide the subscribers andtheir allotted first-selectors into groups of thousands. Eachthousand-group is sub-divided into groups of one hundred. Then the linehundreds that is, the one hundreds, the two hundreds, etc.of the variousthousands are each arranged in a separate group, so that in a tenthousand system the one hundreds of the thousands form one group, thetwo hundreds a second group, etc. Furthermore, each bank level of eachof these hundred-groups has allotted to it one group of second-selectorsallotted to the thousands corresponding to the level-that is, thesecond-selectorgroup of the first-selector first bank level is allottedto the first thousand, the second level to the second thousand, etc.,thus taking care of the thousands. Furthermore, thesecond-selector-groups of each thousand are arranged in one group, andeach bank level in each of these second-selector-groups has allotted toit a group of connectors, which in turn are allotted to the hundred ofthe corresponding thousand corresponding to the level-that is, theconnector-group of the second-selector first bank level falls in thefirst hundred of its thousand, and of the second level in the secondhundred, etc., thus taking care of the hundreds; there being in a tenthousand system ten one-thousandgroups of first-selectors; tenone-hundredgroups in each thousand; ten cross-hundred groups in the tenthousands; also ten groups of second-selectors, one for each thousand;and ten groups of connectors in each thousand,one for each hundred. Withthis arrangement it will be understood that the first level of the firsthundreds in all thousands in the system are multiplied in a manner wellunderstood; likewise the second level, etc. Also, all like levels ofeach second-selector-group (one of which, as stated,

menses is allotted to each thousand) are likewise multiplied. In each ofthe aforesaid c0nnectongrou-psalso, and in the: same manner, the likelevels aremultiplied.

From the foregoing it will be seen that the or'ginating operator at Chas complete supervision over the trunking connectionestablishscdbetween the calling manual sub scribcr and the called automaticsubscribed. This trunking. connection is established by both manual andautomatic apparatus, and through the calling operation oi the originatingand trunking operators the trunkingpperator has complete controlover the automatic portion of the operation-diet is to say, theextension of the connection by automatic switches. The manualsubscribers are furnished with talking current derived from a commonbattery at the exchange or centralstation, and, as herein disclosed, theautomatic subscribers are equipped with 10- cal batteries for talkingpurposes. It will thus be seen that trunking connection is. affordcdbetween common. battery and local battery subscribers, and that thecommon batter, operators have complete supervision over the service thusafifiorded between the subscribers of two different types of exchanges.

What we claim as our invention is:-

l. A telephone exchan e system comprising subscribers lines, an meansfor tnmking calling lines into connection with called lines, said meansincluding anoriglnatin opcrators cord circuit, a trunking operator scord circuit, means rwntrolled by the trunking operator forautomatically extending commotion iron-i the trunking operators positionto the called line, means at the originating operators cord circuit forreceiving a disconnect signal from the calling subsrriber, means at theoriginating operators cord circuit for receiving a disconnect signalfrom the called subscriber, and releasing means controllable by thetrunking operator for automatically disconnecting between the trunkingoperator and the called subscriber.

Q. A telephone system comprising an originating operators' cord circuit,a relay controllin the continuity of said cord circuit, a truu ingoperators cord circuit, a trunk line connecting the two cord circuits,an automatic switch, means for manually extending connection from thetrunking operators cord circuit to s'aid automatic switch, means bywhich the trunking operator controls the operations of saidautomaticswitch, a relay associated with thetrunking operators cord circuit, andan energizing circuit including both of said relays in series with oneside of the trunk line between the two COl'Cl circuits.

3. A telephone system comprising an originating opcrutofs cord cirruit,a trunk line adapted to be connected therewith provided at one end witha trunking operators cord circuit, a relay associated with said trunkinoperatefs cord circuit, a signal controlled by said relay, an automaticswitch, a trunk line leading from the trunking operators cord circuit tothe automatic switch, means at the trunking operators position forcontrolling said automatic switch to find the called line, means forenergizing said relay to display said signal when a connection is madebetween said trunking cord and trunk, and means for deu-er izing saidrelay upon the response of the ca led subscriber.

4. A telephone exchange system comprising subscribers lines, and meansfor trunking calling lines into connection with called lines, said meansincluding originating and trunkin operators cord circuits for extendingthe rst portion of the trunking connection, a plurality of selectors anda connector for completing the trunking connection to the calledsubscribcrs line, means at the trunking operators position forcontrolling the operations of the selectors and connector, and a: signalat said trunking o-perators cord adapted to be displayed when aconnection is made between said cord and one of said selectors andadapted to be extinguished upon the response of the called subscriber.

5. In an automatic and manual telephone exchange system, a trunkingoperators cord circuit terminating at one end in a multiple j aclr and.at its other end in a plug having a voice-current conductor normallyconnected to non-grounded battery, a front supervisory relay and a backsupervisory relay, a pair of signals controlled thereby, the frontsupervisory relayadapted to energize as soon as an originating operatorplugs into the jack to revent the front supervisory signal fromligiiting, a trunk provided with an automatic switch at the end thereof,means causing. the back supervisory relay to energize as soon as thetrunking operator plugs mto said trunk leading to an automatic switchfor causing the back supervisory si 'nal to be displayed, the backsupervisory re ay being adapted to remain energized after con nection ismade with the called line, means causin it to de'energize as soon as thecalled subscn or answers, whereb the back supervisory signal isextinguis 1ed, and means whereby non-grounded battery potential isremoved from said voice-current conductor while said relay is energized,as set forth.

6. In an automatic and manual telephone exchange system, automaticswitches, quick and slow acting relays 114: and 115 controlling therelease of said switches, a cord circuit J, a push-button a for cuttingoil the ground from the quick and slow acting relays 114 and 115, sothat afte a connection has once been set up the trunking operator at Jmay change cords without initiating the release, substantially as setforth.

7. In an automatic and manual telephone exchange system, a subscribersline, a trunking operators cord circuit, a back supervisory relaytherefor, a first selector, :1 second "selector and a connector, arotagy line relay for each of said selectors an connector, and means forenergizing said back supervisory relay in series with said rotary linerelays, as set forth.

8. In an automatic and manual telephone exchange system, manual andautomatic substations, an originating operators oord circuit, a trunkingoperators cord circuit, a back-bridge relay 113 at said originatingoperators cord circuit, a signal lamp con trolled thereby, a backsupervisory relay 168 at the trunking operators cord circuit, a

signal controlled thereby, and a connector F having a backwbrid e relay78 controlled from an automatic su station, which relay in turn controlsthe back supervisory relay 168 at the trunking operators cord circuit,which relay 168 when energized is adapted to deenergize the back-bridgerelay 113 at the originating operators cord circuit, thereby displayingthe signal controlled thereby, and said relay 168 adapted when energizedto display the signal associated therewith.

9. In an automatic and manual telephone exchange system, manual andautomatic substations, an originating operators cord circuit, a trunkingoperators cord circuit, a back-bridge relay 113 at said originatingoperators cord circuit, a signal lamp controlled thereby, a backsupervisory relay 168 at the trunking operators cord circuit, a signalcontrolled thereby, a connector F having a back-bridge relay 78controlled from an automatic substation, meanswhere by the connectorback-bridge relay 78 energizes as soon as connection is made with thecalled line, the back-bridge relay 168 of the trunking operators cordcircuit being therey energized to cause a display of the signalcontrolled thereby, the signal at the originating operators cord circuitbeing displayed at the same time, and means whereby when the calledsubscriber answers at the automatic substation the connector back-bridgerelay 78 and the trunking operators back signal relay 168 denergize,thus retiring the signal lamps at the trunking and originating operatorscord circuits.

10. In an automatic and manual telephone exchange system, a manualsubscribers station A, an originating operators cord circuit C with afront supervisory lamp 177 and a back supervisory lamp 110, a trunkingoperators cord circuit J with a front supervisory lamp 172 and a backsupervisory lamp 171, an order wire 0, a connector switch F with aback-bridge relay 78, an automatic substation A, means whereby when themanual subscriber A removes his receiver the front supervisory lamp 177is displayed at the cord circuit 0, means including the order wire 0whereby the manual operator at C may signal the trunking operator at Jand place an order for connection to an automatic subscriber, andwhereby the trunking operator at J may assign to the operator at G atrunk terminating in the cord circuit J, means whereby when the operatorat C plu into the trunk leading to the cord circuit :J the frontsupervisory lamp 102 of the cord circuit J is displayed, trunks allottedto the trunking operator at J and terminating in an automatic exchange,means whereby when the trunking operator at J plugs into one of saidautomatic trunks the back supervisory lamp 171 of the cord circuit J isdisplayed, means whereby at the same time the back supervisory lamp 110of the cord circuit C is displayed, means allotted to the trunkingoperator at J for establishing an automatic connection including aselector D and a selector E and a connector F, means whereby the backsupervisory lamps 171 and 110 remain displayed after the trunkingoperator J plugs into the automatic trunk and until the calledsubscriber answers, means whereby when the called subscriber answerssaid back supervisory lamps 171 and 110 are retired, means whereby whenthe manual sub scriber at A hangs u his receiver the front supervisorylamp 1 7 is again displayed, means whereby when the automatic subscriberat A hangs up his receiver the back supervisory lamps 171 and 110 areagain displayed, giving the originating operator at C a disconnectsignal by means of lamps 177 and 110, means whereby when the originatingoperator at C disconnects from the trunk circuit J the front supervisorylamp 172 is also displayed, giving the trunking operator at J adisconnect signal, and means whereby when the trunking operator at Jdisconnects from the automatic trunk leading to the automatic exchange arelease of the automatic switches is automatically accomplished.

11. A telephone system comprising an automatic switch, a trunk lineleading thereto, a spring jack for the other end of said .trunk line, anormally closed low resistance ing operator for automatically extending1 connection fromthe trunking operators position to the called line,operated by vertical motion from one level to another to select groupsand by rotary motion in any selected level to connect with a linetherein, means at the originating operators cord circuit for receiving adisconnect signal from the calling subscriber, means at the originatingoperators cord circuit for receiving a disconnect signal from thecalled. subscriber, and releasingmeans controllable by the trunkingoperator for automatically disconnecting between the trunking operatorand the called subscriber.

13. A telephone system comprising an originating operators cord circuit,a relay controlling the continuity of said cord circuit, atrunkingo'perators cord circuit, a trunk line connecting the two cordcircuits, an automatic switch operative by vertical motion from onelevel to another to select groups and. by rotary motion in any selectedlevel to connect with a line therein, means for manually extendingconnection from the trunking operators cord circuit to said automaticswitch, means by which the trunking operator controls the operations ofsaid automatic switch, a relay associated with the trunking operatorscord circuit, and an energizing circuit includin both of said relays inseries with. one si e of the trunk line between the two cord circuits.

14. A telephone system comprising a trunk line terminating at one end ina trunking operators cord circuit, a relay as sociated with said cordcircuit, a signal controlled by said relay, an automatic switchoperative by vertical motion from one level to another to select groupsand by rotary motion in any selected level to connect with a linetherein, a trunk line leading from the trunking operators cord circuitto the automatic switch, means at the trunking operators position forcontrolling said automatic switch, means for energizing said relay todisplay said signal when a connection is made between said trunking cordand trunk, and means for denergizing said relay upon the response of thecalled subscriber.

15'. A telephone exchange system comprising subscribers lines, and meansfor trunking calling lines into connection with called lines. said meansincluding originating and trunking operators cord circuits for extendingthe first portion of the trunking connection, a pluralit of selectorsand an automatic connector or' completing the trunking connection to thecalled subscribers line, operative by vertical motion from one level toanother to select groups and by rotary motion in any selected level toconnect with a line therein, means at the trunking operators positionfor controlling the operations of the selectors and connector, and asignal at said trunking operators cord adapted to be displayed when aconnection is made be tween said cord and one of said selectors andadapted to be extinguished upon the response of'thc called subscriber.

16. A telephone system comprising an automatic switch operative byvertical motion from one level to another to select gronpsand byrotamotion in any selected level to connect wit a line therein, a trunkline leading to said switch, a spring jack for the-other end of saidtrunk line, a normall closed low resistance bridge across said trun linebetween the jack and the automatic switch, a normally open connectionbetween said bridge and the ground, a relay for opening said bridge, arelay for closing said ground connection, and an operators key foropening said ground connection.

17. In an automatic and manual telephone exchange system, a trunkingoperators cord circuit terminating at one end in a multiple jack and atits other end in a plug having a voice-current conductor normallyconnected to non-grounded battery, means including an automatic switchfor extending a. connection. from said cord to a called line, a frontsupervisory relay and a back supervisory relay, a pair of signalscontrolled thereby, the front supervisory relay adapted to energize assoon as an originating operator plugs into the jack to prevent the frontsupervisory signal from lighting, means causing the back supervisoryrelay to energize as soon as the trunking operator plugs into a trunkleading to said automatic switch for causing the back supervisory signalto be displayed, the back supervisory relay being adapted to remainenergized after connection is made with the'called line, means causingit to deenergize as soon as the called subscriber answore, whereby theback supervisory signal iscaused to light, and means whereb nongroundedbattery potential is removed from the voice-current conductor when said,relay is energized, said automatic switch operative by one motion toselect groups and by a second motion to connect with a line in aselected group.

18. In an automatic and manual telephone exchange system, subscriberslines divided into groups, a trunking operators cord circuit, a backsupervisory relay therefor, a second selector, a third selector and aconnector, a rotary line relay for each of said selectors and connector,and means for energizing said back supervisory relay in series with saidrotary line relays, said connector operative by vertical motion from onelevel to another toselect groups and by rotary motion in any selectedlevel to connect with a line therein, as set forth.

19. lin an automatic and manual telephone exchange system, subscriberslines divided into groups, manual and automatic substations, anoriginating operators cord circuit, a trunking operators cord circuit, aback-bridge relay 113 at said originating operators cord circuit, asignal lamp con trolled thereby, a back supervisory relay 168 at thetrunking operators cord circuit, a signal controlled thereby, and aconnector F having a back-bridge relay 78 controlled from an automaticsubstation, which relay in turn controls the back supervisory relay 168at the trunki-n operators cord circuit, which relay 168 when. energizedis adapted to deenergize the back-bridge relay 113 at the originatingo-perators cord circuit thereby displaying the signal controlledthereby, and said relay 168 adapted when energized to display the signalassociated therewith,

said connector operative by vertical motion from one level to another toselect groups and by rotary motion in any selected level. to connectwith a line therein.

20. In an automatic and manual telephone exchange system, subscriberslines divided into groups, manual and automatic substations, anoriginating operators cord circuit, a trunking operators cord circuit, abackbridge relay 113 at said originating operators cord circuit, asignal lamp controlled thereby, a back supervisory relay 168 at thetrunking operators cord circuit, a signal controlled thereby, aconnector F having a back-bridge relay 78 controlled from an automaticsubstation, means whereby the connector back-bridge relay 78 energizesas soon as connection is made with the called line, the backbridge relay168 of the trunking operators cord circuit being thereby energized tocause a display of the signal controlled thereby, the signal at theoriginating operators cord circuit being displayed at the same time, andmeans whereby when the called subscriber answers at the automaticsubstation the connector back-bridge relay 78 and the trunking operatorsback signal relay 168 denergize, thus retiring the signal lamps at thetrunking and originating operators cord circuits, said connectoroperative by vertical motion from one level to another to select groupsand by rotary motion in any selected level ,to connect with a linetherein.

21. In an automatic and manual telephone exchange system, a manualsubscribers station A, an originating operators cord circuit C with afront supervisory lamp 177 and a back supervisory lamp 110, a trunkingoperators cord circuit J with a front supervisory lam 172 and a backsupervisory lamp 171, an order wire 0, a connector switch F with aback-bridge relay 78, said connector operative by vertical motion fromone level to another to select groups and by rotary motion in anyselected level to connect with a line therein, an automatic substationA, means whereby when the manual subscriber A removes his receiver thefront supervisory lamp 177 is displayed at the cord circuit C, meansincluding the order Wire 0 whereby the manual operator at C may signalthe trunking operator at J and place an orderfor connection to anautomatic subscriber, and whereby the trunking operator at J may assignto the operator at O a trunk terminating in the cord circuit J, meanswhereby when the operator at C plugs into the trunk leading to the cordcircuit J the front supervisory lamp 102 of the cord circuit J isdisplayed, trunks allotted to the trunking operator at J and terminatinin an automatic exchange, means whereby w en the trunking operator at Jplugs into one of said automatic trunks the back supervisory lamp 171 ofthe cord circuit J is displayed, means whereby at the same time the backsupervisory lamp 110 of the cord circuit C is displayed, means allottedto the trunking operator at J for establishing an automatic connectionincluding a selector D and a selector E and said connector F, meanswhereby the back supervisory lamps 171 and 110 remain displayed afterthe trunking operator J plugs into the automatic trunk and until thecalled subscriber answers, means whereby when the called subscriberanswers said back supervisory, lamps 171 and 110 are retired, meanswhereby when the manual subscriber at A hangs up his receiver the frontsupervisory lamp 177 is again displayed, means whereby when theautomatic subscriber at A hangs up his receiver the back supervisorylamps 171 and 110 are again dis layed, giving the originating operatorat C a disconnect signal by means of lamps 177 and 110, means wherebywhen the originating operator at O disconnects from the trunk circuit Jthe front su ervisory lamp 172 is also displayed, giving t e trunkingoperator at J a disconnect signal, and means whereby when the trunkingoperator at J disconnects from the automatic trunk leading to theautomatic exchange a release of the automatic switches is automaticallyaccom lished.

22. n a telephone system, a callingand a called subscribers line, anautomatic connector switch for establishing connection with a calledline, means including a plurality of operators circuits for extending aconnection from the calling line to said connector switch, and meansconsisting of signals by which the originating operator supervises theconnections thus established, each signal being adapted to be displayedwhen the corresponding receiver is hung up at the substation.

23. In an automatic and manual tele hone exchange system, subscriberslines divided into groups, a manual operators trunking cord, meansoperative by vertical motion from one level to another to select groupsand by rotary motion in any selected level to connect with a linetherein, electrically controlled release equipment for said means,release circuits for controlling said equipment, energized quick andslow acting relays for controlling the release of said means, and meansincluding a push button for rendering the release circuit inoperative sothat after a connection has once been set up the trunking operator maychange cords without initiating the release.

24:. A telephone system comprising an originating operators cordcircuit, a trunk line adapted to be connected therewith provided at oneend with a trunking operators cord circuit, a relay associated with saidtrunking operators cord circuit, a signal controlled by said relay, anautomatic switch, a trunk line leading from the trunk ing operators cordcircuit to the automatic switch, an impulse sender at the trunkingoperators position for controlling said automatic switch to find thecalled line, a circuit for energizing said relay to display said signalwhen a connection is made between said trunking cord and trunk, and aswitch for deenergizing said relay upon the response of the calledsubscriber.

25. A telephone exchange system comprising subscribers lines, andtrunking circuits for trunking calling lines into connection with calledlines, said trunking circuits including originating and trunkingoperators cord circuits for extending the first portion of the trunkingconnection, a plurality of selectors and a connector for completing thetrunking connection to the called subscribers line, an impulse sender atthe trunking operators position for controlling the operations of theselectors and connector, and a signal at said trunking operators cordadapted to be displayed when a connection is made between said cord andone of said selectors and adapted to be extinguished upon the res onseof the called subscriber.

26. telephone system comprising a trunk line terminating at one end in atrunking operators cord circuit, a relay associated with said cordcircuit, a signal controlled by said relay, an automatic switchoperative by vertical motion from one level to another to select groupsand by rotary motion in any selected level to connect with a linetherein, a trunk line leading from the trunking operators cord circuitto the automatic switch, an impulse sender at the trunking operatorsposition for controlling said automatic switch, a circuit comprising thecalled subscribers line for energizing said relay to display said signalwhen a connection is made between said trunking cord and trunk, and aswitch controlled by the called subscriber for controlling said circuitto deenergize said relay upon the response of the called subscriber.

27. A telephone exchange system comprising subscribers lines, and trunksless in number than the subscribers lines for trunking calling linesinto connection with called lines, said trunks including originating andtrunking operators cord circuits for extending the first portion of thetrunking connection, a plurality of selectors and an automatic connectorfor completing the trunking connection to the called subscribers line,operative by vertical motion from one level to another to select groupsand by rotary motion in any selected level to connect with a linetherein, an impulse sender at the trunk ing operators position forcontrolling the operations of the selectors and connector, a signal atsaid trunking operators cord, a circuit for controlling said signal sothat the same is displayed when aconnection is made between said cordand one of said selectors and retired upon the response of the calledsubscriber.

28. In a telephone system, a calling and a called subscribers line, anautomatic connector switch for establishing connection with a calledline, trunking circuits less in number than the lines including aplurality of operators for extending a connection from the calling lineto said connector switch and a signal for the originating operator forsupervising connections thus established, a circuit for said signal,said signal being under the control of the subscriber on the line calledthrough the medium of said circuit whereby the signal is displayed toindicate that the called subscriber is through talking.

29. In a telephone exchange system, the combination with a plurality ofsubscribers lines terminating in different central ofiices, trunk linesof the two and three conductor type, automatic selector switches,sending mechanism at one of said oiiices adapted to direct said switchesto intercon- --nect said subscribers lines by means of said trunk lines,an established connection including both two-conductor andthree-conductor trunk lines and leading through a plurality of offices,the trunk lines extending to the controlling oflice and from thecontrolling oflice to another office through which the calling line isextended being of the twoconductor type, and signals at said controllingoffice for supervising connections.

Signed by us at Chicago, Cook county, Illinois, this 17th day of April,1907.

WILSON L. CAMPBELL. TALBOT G. MARTIN. Witnesses:

J. NonBY, ARTHUR B. SPERRY.

Copies 01' this patent may be obtained for five cents each, byaddressing the Commissioner of Patents, Washington, D. 0."

